This study is a prospective physiologic study. The primary study population will be adult invasive tracheal intubated patients with COPD, and investigators will collect relevant demographic data, vital signs, and baseline physiologic parameters of the patients prior to the spontaneous breathing test（SBT). The participants will be divided into a successful withdrawal group and a failed withdrawal group according to the SBT outcome, and the changes in the above parameters during SBT will be compared between the two groups .